Locational privacy (aka "location privacy") refers to the ability of
an individual to move in public space with the reasonable expectation
that their location will not be systematically and secretly recorded
for future use.
We are rapidly moving into an era where an abundance of extremely
convenient location-based services (implemented on mobile platforms
like smartphones and in-car devices) pose grave threats to locational
privacy. I'm very concerned about the possibility of this sort of
"information infrastructure" inadvertently building a pervasive
Neither the law nor people's intuition is keeping up with the pace of
technological change; this is a classic example of where the
transition from inexpensive (a policeman follows your car) to free
(the police mine the location database) will cause a dramatic change
in the possibilities for abuse.
It is technically feasible to build systems which balance legitimate
information needs with privacy, using modern cryptography and careful
system design. We need more work on developing practical versions of
such systems, and legislative action to both mandate the use of such systems
in government procurement and to uphold the principle that people own
any information generated about their location.
The Electronic Frontier Foundation (EFF) has an excellent summary page
on the issue.